Systems for activating new users on cellular telephones or mobile stations to a cellular network have been in use for some time. The activation process includes storing customer billing information on the cellular network, and storing shared secret data on both the mobile station and the cellular network. The shared secret data includes a telephone number of the mobile station, information for identifying the manufacturer and serial number of the mobile station, and an authentication key (A-key) used to encrypt data sent between the mobile station and the cellular network. Encrypted data may include both voice and data.
The presence of shared secret data on a mobile station and a cellular network allows sophisticated bi-directional verification techniques to be implemented for authentication of the mobile station to the cellular network in subsequent uses. The bi-directional verification techniques aid in limiting practices of Radio Frequency (RF) ease-dropping for the purpose of gaining unauthorized access to the cellular network with charges being fraudulently billed to an authorized subscriber.
A well-known method for activating a mobile station to a cellular network is over-the-air activation teleservice (OATS) and is described in the Telecommunication Industries Association (TIA) standard document number: IS 136. OATS uses a secure method to generate an A-key in both a mobile station and a cellular network known as the Diffie-Hellman method.
The OATS process commences with a telephone call from a user at a mobile station to a customer service representative for a cellular network. In response to the call from the user, an authentication center at the cellular network begins to generate Diffie-Hellman data encryption values. The data encryption values take several minutes to generate due to rigorous statistical requirements, while the user remains on the phone with a customer service representative. Waiting for the generation of Diffie-Hellman data encryption values causes inconvenience to the user and impairs the ability of a cellular network to activate new users.